Biomarkers for Hunter Syndrome: An International, Multicenter, Observational, Longitudinal Protocol

Mucopolysaccharides are long chains of sugar carbohydrates, found within the cells that help build bone, cartilage, tendons, cornea, skin, and connective tissue. Glycosaminoglycans (GAGs) are also found in the fluids that lubricate joints. Mucopolysaccharidosis (MPS) are part of the Lysosomal Storage Disorder (LSD) family, a group of more than 40 genetic diseases, and occur when a particular enzyme exists in a small quantity or is missing altogether. The effect is the accumulation of GAGs in the cells, blood, and connective tissues, resulting in permanent and progressive cellular damage which affects appearance, physical abilities, organ and system functioning and, in most cases, mental development.

MPS2 (also called Hunter syndrome) is a hereditary, progressive, multisystemic disorder, caused by mutations in the IDS gene coding for the enzyme iduronate sulfatase (Ids). It is the only type of mucopolysaccharidosis that is X-linked, therefore, if mothers are carriers, there is a 50 percent chance for males to be born with the disease.

MPS2 has a wide range of symptoms that vary in severity, which can be managed with enzyme replacement therapy (ERT). ERT is unable to cross the blood-brain barrier, therefore it addresses strictly extra-neurological manifestations. On this note, further efforts are being made to develop novel therapies, in the attempt to stop the disease progression and to offer a better quality of life to the patients.

As MPS2 is very rare and many medical professionals only see a few or no patients in their lifelong practice, genetic testing is crucial for diagnosis. This study thrives to identify, validate, and monitor potential biomarker/s for MPS2 in genetically confirmed samples.